In a vehicle equipped with a motor and an internal combustion engine as drive sources, the motor and the internal combustion engine are driven and controlled so that vehicle-required power required based on the accelerator operation amount and the vehicle speed is obtained. An electric motor-generator is operated by the internal combustion engine to generate electricity, thereby obtaining electricity for driving the motor and the like. When the electric motor-generator is operated by the internal combustion engine to generate electricity, negative torque generated by the electric motor-generator, i.e., torque that suppresses rotation of the engine acts on the engine.
In such a vehicle, the motor, the internal combustion engine, and the electric motor-generator are driven and controlled to reduce energy consumption in the entire vehicle to the extent possible. In the driving and control operation of the internal combustion engine at this time, output torque during operation of the engine is adjusted to a required value that is set based on the vehicle-required power. When electricity is generated by the electric motor-generator through the driving and control operation of the electric motor-generator, the motor is driven using electricity generated at that time, and surplus amount of electricity that cannot be consumed by the driving operation of the motor is stored in a battery mounted in the vehicle.
To improve the fuel economy of the internal combustion engine mounted in the vehicle, it is effective to provide the engine with a forced-induction device. As the internal combustion engine mounted in the vehicle, it is possible to employ an internal combustion engine having a forced-induction device shown in Patent Document 1, for example. The internal combustion engine having the forced-induction device of Patent Document 1 is provided with a variable boost pressure mechanism for adjusting boost pressure of the engine caused by the forced-induction device. When the electric motor-generator, which is operated by the internal combustion engine to generate electricity, is brought into high temperature, the boost pressure of the engine is lowered through a driving and control operation of the variable boost pressure mechanism. In this case, by lowering the boost pressure, output torque of the internal combustion engine can be lowered. Accordingly, it is possible to suppress heat generation when the electric motor-generator is operated to generate electricity by the engine, and to protect the electric motor-generator.